An attachment for existing bicycle racks to permit the use of expandable and rotatable arms was disclosed in my prior U.S. Pat. Nos. 5,222,639 and 5,217,149. The use of the rotatable and axially movable arms extending from opposite sides of a pair of tubular members as disclosed in these patents has proved commercially successful. However, the various embodiments of the attachments disclosed in the patents posed some problems as regards cost-effective mass production, assembly and use. Once a fastening screw normally holding a support arm in its selected position was loosened, there existed the danger of inadvertent complete pull out or fall-out of the support arm out of the tubular members, particularly during axial adjustment of the support arms. Additionally, overtorquing during tightening of the screws holding the support arms could result in relatively costly repairs.
My prior U.S. Pat. No. 5,217,149 already proposed to integrate the attachment into a bicycle rack, and for that purpose suggested to connect the tubular members of the accessory by welding from below to the longitudinal frame members so that the support arms came to lie a distance below the load bearing surface formed by the frame itself.